The objectives of this proposal are to determine the effect beta-lactamases produced by the subgingival microbiota may have on the potential usage of penicillins and cephalosporins in periodontal therapy. Gingival fluid samples and attachment levels will be taken on 50 periodontally diseased patients, most of whom will fit into distinct clinical classifications. Gingival fluid samples will be tested for beta-lactamase by a sensitive biochemical assay developed for this purpose. The amount of the enzyme present, the attachment level, and the disease syndrome will be statistically examined to determine if correlations exist between any of these factors. Subgingival plaque samples will be taken from 30-40 sites having the highest beta-lactamase activities; approximately 20 penicillin-resistant isolates from each site will be purified and tested for beta-lactamase. The beta-lactamase-producing bacteria will be characterized, identified, and antibiotic susceptibilities determined to 8 beta-lactam compounds. Beta-lactamases produced by 50 of these bacteria will be isolated, purified, and characterized further. The isolectric point as well as the affinity and hydrolytic activity of these enzymes for beta-lactam substrates and inhibitors will be determined. The incidence of beta-lactamase associated with specific periodontal disease syndromes will be combined with the subceptibilities of the bacteria and the enzymes' activities against beta-lactam antibiotics to determine which pencillins and cephalosporins may be of use in the treatment of certain periodontal diseases.